Insulating compound.



UNITED STATES PATENT OFFICE.

PATRICK J. CANNON, WILLIAM H.. roU NG, AND OLSINTON BAT'EHOLTS, OESGHENEOTADY, NEW ronnnssrenoss TO GENERAL ELECTRIC COMPANY, A CORPORATION or NEW YORK.

Specification of Letters Patent.

INSU'QLATING ooMPoUNn.

Patented Jan. 26, 1909.

To all whom it may concern: a I

Be it known that we, PATRICK J. CANNON,

WILLIAM H. YOUNG, and CLINTON BATE- boiling water and of lower cost than the insu lating substances heretofore in use.

Our invention consists, speaking generally, of a composition made by mixing of a relatively large proportion of comminuted inert material, a quantity of fibrous matter sufficient to give the finished product its desired tensile strength and toughness and an amount of prepared resinous substance which is made by the application of heat to unite intimately with the inert matter, and subjecting the heated mixture to pressure in a suitable mold from which it may be removed when cooled in its finished state.

The inert material may be clay, sand, ground stone, or any other refractory substance having good insulating properties. We have found ground slate to possess both mechanical and dielectric properties to a highly satisfactory degree ';in compositions for use upon trolley-Wire suspenders and similar appliances. The degree of comminution will vary according to the strength and general appearance desiredin the finished article.

The fibrous matter which serves as a binder for the composition may be of asbestos or other dielectric fibrous material. We have used amiXture of the cheaper grades of asbestos, such as'yellow, and short white either singly or together in equal amounts, and a small quantity of a better grade in the proportion of about '94 pounds of the former grade or grades to six of the latter grade with good results. i

The resinous substance which we employ consists, for the larger part, of the cheaper grades of copal with the addition of a bituminous substance such as asphaltum or gilsoirite whereby the meltingtemperature of the resinous substance may be raised as much as desired above the highest temperature to which the insulation will be subjected in practice. A resinous substance consisting of twenty-six parts kauri,for,ty-five parts copal dust or chips, twenty-two parts gilsonite and;

seven parts ordinary rosin produces anexcellent gumand at a very low cost. The several constituents may be mixed 1n various proportions according to the service to which the insulation composition will be subjected in practice, that is to say, in places where great mechanical strength is not required, the proportion of inert material may be greatly-increased and Where great tensile strength is required the resinous substance or the fibrousv material will be increased. We have found, however, that for ordinary purposes the following proportions produce an insulating composition which is thoroughly satisfactory in practice and of very low cost; viz., about sixty-seven parts of comminuted inert material (preferably ground slate) ten parts of asbestos, and

twenty-three parts of resinous substance prepared as above described. These ingredients are thoroughly commingled and heated in anysuitable manner to 380 degrees Fahrenheit at which temperature the resinous substance is rendered viscous and readily combines with the other ingredients. The composition is placed while heated into hot iron molds and subjected to pressure which varies according to the use for which the particular article is intended. When the mold has become cooled the finished article may be removed in the ordinary manner.

We do not desire to restrict ourselves to the )articular ingredients or the method of combination thereof above described, since it is apparent that they may be changed and modified Without departing from our invention.

What we claim as new and desire to secure by Letters Patent of the United States, is,-

1. An electrical insulating compound moldable into desired shapes by the application of heat and pressure and consisting of comminuted inert material, and a binder comprising cop il gum and a bituminous-sub- I able into desired shapes by the application of heat and pressure and consisting of ground slate, asbestos and a binder comprising copal gum-and gilsonite' v 3. A moldable insulating compound con- 5 sisting of ground inert material, and a binder com rising copal and kauri 'gums rendered less usible by the admixture therewith of a small amount of gilsonite.

4. A moldable insulating compound con- 10 sisting cf-the following constituents in about theproportions specified to Wit: sixty-seven parts of inert material. ten parts of asbestos, six parts of kauri, ten parts of copal, five parts of gilsonite and two parts of rosin.

In witness whereof, we have hereunto set 15 our hands this 24th day of December. 1903.

PATRICK J. CANNON. WILLIAM H. YOUNG.

CLINTON BATEHOLTS Witnesses BENJAMIN B. HULL, MARGARET E. WOOLLEY. 

